Denali National Park and Preserve is an American national park and preserve located in Interior Alaska, centered on Denali, the highest mountain in North America. The park and contiguous preserve encompass 6,045,153 acres (9,446 sq mi; 24,464 km2) which is larger than the state of New Hampshire.[3] On December 2, 1980, 2,146,580-acre (3,354 sq mi; 8,687 km2) Denali Wilderness was established within the park. Denali's landscape is a mix of forest at the lowest elevations, including deciduous taiga, with tundra at middle elevations, and glaciers, snow, and bare rock at the highest elevations. The longest glacier is the Kahiltna Glacier. Wintertime activities include dog sledding, cross-country skiing, and snowmobiling. The park received 594,660 recreational visitors in 2018.

Human habitation in the Denali Region extends to more than 11,000 years before the present, with documented sites just outside park boundaries dated to more than 8,000 years before present. However, relatively few archaeological sites have been documented within the park boundaries, owing to the region's high elevation, with harsh winter conditions and scarce resources compared to lower elevations in the area. The oldest site within park boundaries is the Teklanika River site, dated to about 7130 BC. More than 84 archaeological sites have been documented within the park. The sites are typically characterized as hunting camps rather than settlements, and provide little cultural context. The presence of Athabaskan peoples in the region is dated to 1,500 - 1,000 years before present on linguistic and archaeological evidence, while researchers have proposed that Athabaskans may have inhabited the area for thousands of years before then. The principal groups in the park area in the last 500 years include the Koyukon, Tanana and Dena'ina people.[4]

Other prehistoric finds include Mesozoic fossils from the Denali Region; trackways from therizinosaurids and hadrosaurids in the Cantwell Formation indicate the area was once an immigration point for dinosaurs traveling between Asia and North America during the Late Cretaceous period. Studies of fossil plants from the same formation indicate the area was wet, with marshes and ponds throughout the region.[5]

In 1906, conservationist Charles Alexander Sheldon conceived the idea of preserving the Denali region as a national park. He presented the plan to his co-members of the Boone and Crockett Club. They decided that the political climate at the time was unfavorable for congressional action, and that the best hope of success rested on the approval and support from the Alaskans themselves. Sheldon wrote, "The first step was to secure the approval and cooperation of the delegate who represented Alaska in Congress."[citation needed]

In October 1915, Sheldon took up the matter with Dr. E. W. Nelson of the Biological Survey at Washington, D.C. and with George Bird Grinnell, with a purpose to introduce a suitable bill in the coming session of Congress. The matter was then taken to the Game Committee of the Boone and Crockett Club and, after a full discussion, it received the committee's full endorsement.

On December 3, 1915, the plan was presented to Alaska's delegate, James Wickersham, who after some deliberation gave his approval. The plan then went to the Executive Committee of the Boone and Crockett Club and, on December 15, 1915, it was unanimously accepted. The plan was thereupon endorsed by the Club and presented to Stephen Mather, Assistant Secretary of the Interior in Washington, D.C., who immediately approved it.

The bill was introduced in April, 1916, by Delegate Wickersham in the House and by Senator Key Pittman of Nevada in the Senate. Much lobbying took place over the following year, and on February 19, 1917, the bill passed. On February 26, 1917, 11 years from its conception, the bill was signed in legislation by the President of the United States, Woodrow Wilson, thereby creating Mount McKinley National Park.[6][7]

A portion of Denali, excluding the summit, was included the original park boundary. On Thanksgiving Day in 1921, the Mount McKinley Park Hotel opened.[8] In July 1923, President Warren Harding stopped at the hotel, on a tour of the length of the Alaska Railroad, during which he drove a golden spike signaling its completion at Nenana.[citation needed]

The hotel was the first thing visitors saw stepping down from the train. The flat-roofed, two-story log building featured exposed balconies, glass windows, and electric lights. Inside were two dozen guest rooms, a shop, lunch counter, kitchen, and storeroom. By the 1930s, there were reports of lice, dirty linen, drafty rooms, and marginal food, which led to the hotel's eventually closing.[citation needed]

In 1947, the park boundaries expanded to include the area of the hotel and railroad. After being abandoned for many years, the hotel was destroyed in 1950 by a fire.[citation needed]

There was no road access to the park entrance until 1957. Now with a highway connection to Anchorage and Fairbanks, park attendance greatly expanded: there were 5,000 visitors in 1956 and 25,000 visitors by 1958.

The name of Mount McKinley National Park was subject to local criticism from the beginning of the park. The word Denali means "the high one" in the native Athabaskan language and refers to the mountain itself. The mountain was named after newly elected US president William McKinley in 1897 by local prospector William A. Dickey. The United States government formally adopted the name Mount McKinley after President Wilson signed the bill creating Mount McKinley National Park into effect in 1917.[9] In 1980, Mount McKinley National Park was combined with Denali National Monument, and the Alaska National Interest Lands Conservation Act named the combined unit the Denali National Park and Preserve. At that time the Alaska state Board of Geographic Names changed the name of the mountain to Denali. However, the U.S. Board on Geographic Names did not recognize the change and continued to denote the official name as Mount McKinley. This situation lasted until Aug. 30, 2015, when President Barack Obama directed Secretary of the InteriorSally Jewell to rename the mountain to Denali, using statutory authority to act on requests when the Board of Geographic Names does not do so in a "reasonable" time period.[10]

In 1992, Christopher McCandless ventured into the Alaskan wilderness and settled in an abandoned bus in the park, off the Stampede Trail, near Lake Wentitika. He carried little food or equipment, and hoped to live simply for a time in solitude. Almost four months later, McCandless' starved remains were found, weighing only 67 pounds (30 kg).[citation needed] His story has been widely publicized via articles, books, and films, and the bus in which his remains were found has become a shrine of sorts, attracting pilgrimages by people from around the world, many of whom leave tributes in McCandless' memory.[11]

Denali National Park and Preserve includes the central, highest portion of the Alaska Range, together with many of the glaciers and glacial valleys running southwards out of the range. To the north the park and preserve encompass the valleys of the McKinley, Toklat and Foraker Rivers, as well as the Kantishna and Wyoming Hills. The George Parks Highway runs along the eastern edge of the park, crossing the Alaska Range at the divide between the valleys of the Chultina River and the Nenana River. The entrance to the park is about 11 miles (18 km) south of Healy. The Denali Visitor Center and the park headquarters are located just inside the entrance. The park road parallels the Alaska Range for 92 miles (148 km), ending at Kantishna. Preserve lands are located on the west side of the park, with one parcel encompassing areas of lakes in the Highpower Creek and Muddy River areas, and the second preserve area covering the southwest end of the high Alaska Range around Mount Dall. In contrast to the park, where hunting is prohibited or restricted to subsistence hunting by local residents, sport hunting is allowed in the preserve lands.[15]

The park is serviced by the 91-mile (146 km) long Denali Park Road, which begins at the George Parks Highway and continues to the west, ending at Kantishna. Located 1 mile (1.6 km) within the park, the Wilderness Access Center (which houses a small gift shop, a coffee stand, and an information desk) is the main location to arrange a bus trip into the park, or reserve/check-in for a campground site. All shuttle buses depart from here, as do some tours. The Denali Visitor Center is at mile marker 1.5 on the park road and is the main source of visitor information. Most ranger-led programs begin at the Denali Visitor Center. Other features include an exhibit hall. Within a short walking distance from the Visitor Center are a restaurant, a bookstore, the Murie Science and Learning Center, the Denali National Park railroad depot, and the McKinley National Park Airport.[citation needed]

The Denali Park Road runs north of and roughly parallel to the imposing Alaska Range. Only a small fraction of the road is paved because permafrost and the freeze-thaw cycle would create a high cost for maintaining a paved road. The first 15 miles (24 km) of the road are available to private vehicles, allowing easy access to the Riley Creek and Savage River campgrounds. Private vehicle access is prohibited beyond the Savage River Bridge. There is a turn around for motorists at this point, as well as a nearby parking area for those who wish to hike the Savage River Loop Trail. Beyond this point, visitors must access the interior of the park through tour/shuttle buses.[citation needed]

The tours travel from the initial boreal forests through tundra to the Toklat River or Kantishna. Several portions of the road run alongside sheer cliffs that drop hundreds of feet at the edges. There are no guardrails. As a result of the danger involved, and because most of the gravel road is only one lane wide, drivers must be trained in procedures for navigating the sharp mountain curves, and yielding the right-of-way to opposing buses and park vehicles.[citation needed]

Road map with camping locations, visitor centers, and ranger stations

There are four camping areas located within the interior of the park (Sanctuary River, Teklanika River, Igloo Creek, and Wonder Lake). Camper buses provide transportation to these campgrounds, but only passengers camping in the park can use these particular buses. At mile marker 53 on road is the Toklat River Contact Station. All shuttle and tour buses make a stop at Toklat River. The contact station features rest rooms, visitor information, and a small bookstore. Eielson Visitor Center is located four hours into the park on the road (at mile marker 66). It features restrooms, daily ranger-led programs during the summer, and on clear days, views of Denali and the Alaska Range. Wonder Lake and Kantishna are a six-hour bus ride from the Visitors Center. During the winter, only the portion of the Denali Park Road near the Visitors Center remains open.[citation needed]

Kantishna features five lodges: the Denali Backcountry Lodge, Kantishna Roadhouse, Skyline Lodge, Camp Denali and North Face Lodge. Visitors can bypass the six hour bus ride and charter an air taxi flight to the Kantishna Airport. The Kantishna resorts have no TV's, and there is no cell phone service in the area. Lodging with services can be found in McKinley Park, one mile north of the park entrance on the George Parks Highway. Many hotels, restaurants, gift shops, and a convenience store are located in Denali Park.[citation needed]

While the main park road goes straight through the middle of the Denali National Park Wilderness, the national preserve and portions of the park not designated wilderness are even more inaccessible. There are no roads extending out to the preserve areas, which are on the far west end of the park. The far north of the park, characterized by hills and rivers, is accessed by the Stampede Trail, a dirt road which effectively stops at the park boundary near the "Into the Wild" bus. The rugged south portion of the park, characterized by large glacier-filled canyons, is accessed by Petersville Road, a dirt road that stops about 5 miles (8.0 km) outside the park. The mountains can be accessed most easily by air taxis that land on the glaciers. Kantishna can also be reached by air taxi via the Purkeypile Airport, which is just outside the park boundary.[citation needed]

Visitors who want to climb Denali need to obtain a climbing permit first, and go through an orientation as well. These can be found at the Walter Harper Talkeetna Ranger Station in Talkeetna, Alaska, about 100 miles (160 km) south of the entrance to Denali National Park and Preserve. This center serves as the center of mountaineering operations. It is open year-round.[citation needed]

The Denali Wilderness is a wilderness area within Denali National Park and Preserve that protects the higher elevations of the central Alaska Range, including Denali. The wilderness comprises about one-third of the current national park and preserve—2,146,580 acres (3,354 sq mi; 8,687 km2) that correspond with the former park boundaries from 1917 to 1980.[16]

Denali National Park and Preserve is located in the central area of the Alaska Range, a mountain chain extending 600 miles (970 km) across Alaska. Its best-known geologic feature is Denali, formerly known as Mount McKinley. Its elevation of 20,310 feet (6,190.5 m) makes it the highest mountain in North America. Its vertical relief (distance from base to peak) of 18,000 feet (5,500 m) is the highest of any mountain in the world. The mountain is still gaining about 1 millimetre (0.039 in) in height each year due to the continued convergence of the North American and Pacific Plates. The mountain is primarily made of granite, a hard rock that does not erode easily; this is why it has retained such a great height rather than being eroded.

There are three major rock provinces that run in east-west bands through the park. The oldest is in the north, and the younger ones in the south.[citation needed] The area is characterized by collision tectonics: over the past millions of years, exotic terranes in the Pacific Ocean have been moving toward the North American landmass and accreting, or attaching, to the area that now makes up Alaska.

The oldest rocks in the park are part of the Yukon-Tanana terrane. They originated from ocean sediments deposited between 400 million and 1 billion years ago. The original rocks have been affected by the processes of regional metamorphism, folding, and faulting to form rocks such as schist, quartzite, phyllite, slate, marble, and limestone.

The next oldest group of rocks is the Farewell terrane. It is composed of rocks from the Paleozoic era (250-500 million years old). The sediments that make up these rocks were deposited in a variety of marine environments, ranging from deep ocean basins to continental shelf areas. The abundant marine fossils are evidence that around 380 million years ago, this area had a warm, tropical climate.

The Pingston, McKinley, and Chulitna terranes are the next oldest; they were deposited in the Mesozoic era. The rock types include marble, chert, limestone, shale, and sandstone. There are intrusions of igneous rocks, such as gabbro, diabase, and diorite. Special features include pillow basalts, which are formed when molten lava flows into water and a hard outer crust forms, making a puffy, pillow shaped feature; as well as an ophiolite sequence, which is a distinct sequence of rocks indicating that a section of oceanic crust has been uplifted and thrust onto a continental area.

Polychrome Mountain

Some of the youngest rocks in the park include the Kahlitna terrane, which is a flysch sequence (a sedimentary rock sequence deposited in a marine environment during the early stages of mountain building) formed about 100 million years ago, during late Cretaceous time. Another rock sequence is the McKinley Intrusive Sequence, which includes Denali. The Cantwell Volcanics include basalt and rhyolite flows, as well as ash deposits. An example can be seen at Polychrome Pass in the park.[17]

Denali National Park and Preserve is located in an area of intense tectonic activity: the Pacific Plate is subducting under the North American plate, creating the Denali fault system, which is a right-lateral strike-slip fault over 720 miles (1,160 km) long. This is a part of the larger fault system which includes the famous San Andreas Fault of California. Over 600 earthquakes occur in the park each year, helping seismologists to understand this fault system. Most of these earthquakes are too small to be felt, although two large earthquakes did occur in 2002. On October 23, 2002 a magnitude 6.7 earthquake occurred in the park, and on November 3, 2002, a magnitude 7.9 earthquake occurred. These earthquakes did not cause a significant loss of life or property, since the area is very sparsely populated, but they did trigger thousands of landslides.[18]

Painting of the heavily glaciated southern part of Denali, looking north-northwest. Mount Foraker is at the left, and Denali, purposely drawn on an exaggerated scale, is featured in the center. Mouse over the painting, and click on an area of interest.

Glaciers cover about 16% of the 6 million acres of Denali National Park and Preserve. There are more extensive glaciers on the southeastern side of the range because more snow is dropped on this side from the moisture-bearing winds from the Gulf of Alaska. The 5 largest south-facing glaciers are Yentna (20 miles (32 km) long), Kahiltna (30 miles (48 km)), Tokositna (23 miles (37 km)), Ruth (31 miles (50 km)), and Eldrige (30 miles (48 km)).[17] The Ruth glacier is 3,800 feet (1,200 m) thick.[18] However, the largest glacier, Muldrow Glacier (32 miles (51 km) long), is located on the north side. Nonetheless, the northern side has smaller and shorter glaciers overall. Muldrow glacier has "surged" twice in the last hundred years. Surging means that it has moved forward for a short time at a greatly increased rate of speed, due to a build-up of water between the bottom of the glacier and the bedrock channel floating on the ice (due to hydrostatic pressure).[17]

At the upper ends of Denali’s glaciers are steep-walled semicircular basins called cirques. Cirques form from freeze-thaw cycles of meltwater in the rocks above the glacier, and by glacial erosion and mass wasting occurring under the glacier. As cirques on the opposite sides of a ridge are cut deeper into the divide, they form a narrow, sharp, serrated ridge called an arête. As the arête wears away from glacial ice breaking it down, the low point between cirques is called a col (or if it is large, a pass). Cols are saddle-shaped depressions in the ridge between cirques. A spire-like sharp peak, called a horn, is formed when cirques cut back into a mountaintop from three or four sides.

Glaciers deposit rock fragments, but the most notable of the depositions are the erratics, which are large rock fragments carried some distance from the source, found on glacial terraces and ridge tops in many places throughout Denali. Headquarter erratics are made of granite and can be the size of a house. Some erratics (like those from the Yanert Valley) are located 30 miles (48 km) away from their original location.

Ruth Glacier and medial moraine - the dark stripe of debris down the middle

Large amounts of rock debris are carried on, in, and beneath the ice as the glaciers move downslope. Lateral moraines are created as debris accumulates as low ridges of till that ride along the edge of the moving glaciers. When lateral moraines adjacent to each other join, they create medial moraines, which are also carried down on the surface of the moving ice.

Kettles are formed when glacial retreat and melting is rapid, and blocks of ice are still buried under till. When the ice under the till melts, the till slumps in and forms depressions called kettles. When kettles fill with water, they are known as kettle lakes. The most famous kettle lake in Denali is Wonder Lake.[citation needed] Near Kantishna, it is the result of both glacial erosion and ice-block melting. It is about 4 miles (6.4 km) long and 280 feet (85 m) deep.

During the very cold Pleistocene climates, all of Denali was solidly frozen. In the northern areas of the range, it is very much still frozen due to continued cold temperatures. Permanently frozen ground is known as permafrost. In Denali, the permafrost is discontinuous, meaning due to difference in vegetation, temperatures, snow cover, hydrology, etc., not all of the ground is solidly frozen. The active layer (the layer that freezes and thaws seasonally) can be from 1 inch (25 mm) to 10 feet (3.0 m) thick. The permafrost layer below the active layer has been measured to be between 30 and 100 feet (9.1 and 30.5 m) deep depending on the location of measurement in the park. A stand of white spruce growing on a lower slope of Denali is called the Drunken Forest because of the oddly leaning trees which seem to look "drunk." This appearance is due to the sliding soil beneath them, due to the permafrost difference and freeze-thaw oscillations that occur due to differences in temperature, vegetation, and hydrology.

Shallow ponds in Denali are known as thaw lakes and cave-in lakes. They form where sunwarmed water has melted basins in the underlying permafrost. They deepen gradually in the summer months depending on the temperature variance. If the temperature is high enough, the thaw lakes and cave-in lakes will enlarge as their rims collapse.

Ice has 10 percent greater volume than water, so it continues to exert pressure on the ground. Thermal expansion and contraction can cause cracks to develop in the permafrost. During the thaw season in the freeze-thaw cycle, water gets into the cracks and forms veins of ice called ice wedges. Ice wedges enlarge with successive seasons of freezing and thawing. Some ice wedges that have been buried for centuries are revealed during excavations or landslides.[17]

Long winters are followed by short growing seasons. Eighty percent of the bird population returns after cold months, raising their young. Most mammals and other wildlife in the park spend the brief summer months preparing for winter and raising their young.

Summers are usually cool and damp, but temperatures in the 70s are not rare. The weather is so unpredictable that there have even been instances of snow in August.

The north and south side of the Alaskan Range have a completely different climate. The Gulf of Alaska carries moisture to the south side, but the mountains block water to the north side. This brings a drier climate and huge temperature fluctuations to the north. The south has transitional maritime continental climates, with moister, cooler summers and warmer winters.

The Alaska Range is a mountainous expanse running through the entire park, strongly influencing the park's ecosystems. Vegetation in the park depends on the altitude. The treeline is at 2,500 feet (760 m), causing most of the park to be a vast expanse of tundra. In the lowland areas of the park, such as the western sections surrounding Wonder Lake, spruces and willows dominate the forest. Most trees and shrubs do not reach full size, due to unfavorable climate and thin soils. There are three types of forest in the park: from lowest to highest, they are low brush bog, bottomland spruce-poplar forest, upland spruce-hardwood forest. The forest grows in a mosaic, due to periodic fires.

In the tundra of the park, layers of topsoil collect on rotten fragmented rock moved by thousands of years of glacial activity. Mosses, ferns, grasses, and fungi grow on the topsoil. In areas of muskeg, tussocks form and may collect algae. The term 'muskeg' includes spongy waterlogged tussocks as well as deep pools of water covered by solid-looking moss. Wild blueberries and soap berries thrive in the tundra and provide the bears of Denali with the main part of their diet.

Over 450 species of flowering plants fill the park and can be viewed in bloom throughout summer. Images of goldenrod, fireweed, lupine, bluebell, and gentian filling the valleys of Denali are often used on postcards and in artwork.

Ten species of fish, including trout, salmon, and Arctic grayling, share the waters of the park. Because many of the rivers and lakes of Denali are fed by glaciers, glacial silt and cold temperatures slow the metabolism of the fish, preventing them from reaching normal sizes.[citation needed] A single amphibious species, the wood frog, also lives among the lakes of the park.

Denali park rangers maintain a constant effort to keep the wildlife wild by limiting the interaction between humans and park animals. Feeding any animal is strictly forbidden, as it may cause adverse effects on the feeding habits of the creature. Visitors are encouraged to view animals from safe distances. In August 2012 the park experienced its first known fatal bear attack when a lone hiker apparently startled a large male grizzly while photographing it. Analysis of the scene and the hiker's camera strongly suggest he violated park regulations regarding backcountry bear encounters, which all permit holders are made aware of.[22] Certain areas of the park are often closed due to uncommon wildlife activity, such as denning areas of wolves and bears or recent kill sites.